The present invention relates to a heat exchanger preferably used as an evaporator of a car air conditioner, which is a refrigeration cycle to be mounted on, for example, an automobile.
Herein and in the appended claims, the upper and lower sides of FIGS. 1 and 2 will be referred to as “upper” and “lower,” respectively.
The applicant of the present application has proposed a heat exchanger used as an evaporator for a car air conditioner which satisfies the needs of reducing size and weight and enhancing performance (see Japanese Patent Application Laid-Open (kokai) No. 2006-132920). The heat exchanger includes a heat exchange core section in which heat exchange tube groups are arranged in two rows in a front-rear direction, each heat exchange tube group consisting of a plurality of heat exchange tubes arranged at intervals; a refrigerant inlet/outlet header tank disposed on an upper-end side of the heat exchange core section; and a refrigerant turn header tank disposed on a lower-end side of the heat exchange core section. A refrigerant inlet header section and a refrigerant outlet header section are integrally provided and arranged side by side in the front-rear direction within the refrigerant inlet/outlet header tank. The refrigerant inlet header section has a refrigerant inlet at a first end, and is closed at a second end opposite the first end. The refrigerant outlet header section has a refrigerant outlet at a first end corresponding to the refrigerant inlet, and is closed at a second end opposite the first end. A first intermediate header section, which faces the refrigerant inlet header section, and a second intermediate header section, which faces the refrigerant outlet header section, are integrally provided and arranged side by side in the front-rear direction within the refrigerant turn header tank. Upper end portions of the heat exchange tubes of a front heat exchange tube group are connected to the refrigerant inlet header section, and upper end portions of the heat exchange tubes of a rear heat exchange tube group are connected to the refrigerant outlet header section. Lower end portions of the heat exchange tubes of the front heat exchange tube group are connected to the first intermediate header section, and lower end portions of the heat exchange tubes of the rear heat exchange tube group are connected to the second intermediate header section. The interior of the refrigerant inlet header section is divided into two spaces; specifically, upper and lower spaces, by means of a plate-shaped partition member. Refrigerant flows into the first (upper) space via the refrigerant inlet, and the heat exchange tubes project into the second (lower) space. The partition member has a communication opening which is formed at a location between the second end opposite the refrigerant inlet and a heat exchange tube closest to the second end so as to establish communication between the first and second spaces. Thus, the refrigerant is caused to flow from the first space into the second space via the communication opening while changing its flow direction to make a U-turn.
However, as a result of various studies, the present inventor has found that the evaporator described in the above-described publication has the following problems.
That is, especially in a case where the amount of refrigerant is large, when the refrigerant flows from the first space to the second space of the refrigerant inlet header section via the communication opening, due to the force of the flow, the refrigerant hits against a portion of a wall of the refrigerant inlet header section to which the heat exchange tubes are connected, the portion being generally located just under the communication opening, and changes its flow direction toward the partition member, so that the refrigerant encounters difficulty in flowing into several heat exchange tubes which are located at an end portion opposite the refrigerant inlet. As a result, outflow air temperature, which is the temperature of air having passed through the evaporator, becomes slightly non-uniform at the end portion opposite the refrigerant inlet, and in some cases the degree of uniformity of the outflow air temperature becomes insufficient.